Nowadays, the applications of flat panel displays in 3C products such as mobile phones, personal digital assistants (PDAs), global positioning systems (GPS), and digital cameras are closely related to people's daily life. Transparent displays, which not only display images or data but further allow users to view the images behind the display, may be used in vending machines, window displays, mall food displays, and museum displays. Display media such as liquid crystal displays (LCD), organic light emitting diode (OLED) displays, and electrowetting displays (EWD) may all be used in transparent displays.
In a transparent display, since metal wires, thin film transistor (TFT), or the ink contraction zone of the electrowetting display all are impermeable to the light, the background light coming from the back of the display has insufficient transmittance, largely affecting users' viewing the images behind the display.